Squeezing of light and atoms in optical magnetometers
Squeezed light was proposed thirty years ago as a way to improve the sensitivity of gravitational-wave interferometers, and is now being put into practice in full-scale instruments such as LIGO. Squeezing of atoms can in principle improve the sensitivity of atomic instruments such as clocks, gravimeters, and optical magnetometers, although as always ``the devil is in the details.'' Optical magnetometers are particularly interesting from a quantum optical point of view because they combine an atomic system (the sensor) with an optical system (for readout). I will discuss recent experiments to understand the quantum physics of optical magnetometers, including use of polarization-squeezed light to improve the sensitivity of a rubidium-vapor magnetometer and spin squeezing to improve the sensitivity of a cold-atom magnetometer. As time permits, I will comment on the new area of nonlinear quantum metrology, which promises to be particularly important for quantum enhancement of optical magnetometry.
Certified quantum non-demolition measurement of a macroscopic material system
R.J.Sewell, M.Napolitano, N.Behbood, G.Colangelo, M.W.Mitchell
http://arxiv.org/abs/1303.2490 (to appear in Nature Photonics)
Magnetic sensitivity beyond the projection noise limit by spin squeezing
R. J. Sewell, M. Koschorreck, M. Napolitano, B. Dubost, N. Behbood, M. W. Mitchell
Phys. Rev. Lett. 109, 253605 (2012)
Squeezed-light optical magnetometry
F. Wolfgramm, A. Cerè, F. A. Beduini, A. Predojević, M. Koschorreck, M. W. Mitchell
Phys. Rev. Lett. 105, 053601 (2010)
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